The present invention relates to a ceramic product used in a place where water is used, for example, in a toilet, kitchen or lavatory in a house. Such a ceramic product includes flush toilets, wash basins, etc. The invention further relates to a method of stain resistant treatment applied to the ceramic product.
Ceramic products such as flush toilets come into contact with human waste, aqueous solution of soap, cleansing liquid, shampoo, lipstick, hairdye, etc. as well as with water in their use. In view of this, a vitreous glazed layer is formed on an inner surface etc. of the ceramic product so that stain such as human waste can easily be eliminated. Furthermore, an antibacterial treatment causing an oligodynamic reaction has recently been applied to the glazed layer for prevention of production of slime and urinary calculus resulting from these stains. Furthermore, the human waste, soap liquid, cleansing liquid, shampoo, hairdye, etc. are aqueous. These adhere to the inner surface of the ceramic product together with water and thereafter dry into stain. In view of this, a water repellent treatment is applied to a glazed surface so that these materials are prevented from remaining on the glazed surface.
However, results of experiments conducted by the inventors that the stain of the ceramic products is a combination of a hydroxyl group present on the glazed surface with components of the human waste etc. and not the dried human waste etc. remaining on the glazed surface. The combination of the hydroxyl group with the components of the human waste etc. is made via dehydration or dehydrogenation between the hydroxyl and metal ion in water. of such metal ions, soluble silica is particularly considered to be deposited as silicic acid with network structure or silicic scale and apt to incorporate stain.
According to results of investigation carried out by the inventors, service waters and mineral waters which are obtained all over Japan and are generally considered to contain no stain actually each contain about 10 p.p.m. of soluble silica on the average as shown by p.p.m. in the following TABLES 1 to 4.
The aforesaid ceramic product is used with water containing a large quantity of the metal ion such as soluble silica, stain such as human waste is apt to adhere to the ceramic product. It is difficult to clean the ceramic product.
The present invention has been made in view of the foregoing and an object thereof is to provide a ceramic product which is subjected to water in use and which has a high stain preventive effect and a method of stain resistant treatment applied to the ceramic product.
To solve the aforesaid problem, the present invention provides a ceramic product having a treated surface formed with a layer composed of a stain resistant agent, said agent including a silicon-containing functional group combining with a hydroxyl group present on the treated surface by dehydration or dehydrogenation.
The invention also provides a method of stain resistant treatment applied to a ceramic product used with water and having a treated surface on which a layer comprising a stain resistant agent is formed so that a stain resistant treatment is applied to the ceramic product, the stain resistant agent including a silicon-containing functional group combining with a hydroxyl group present on the treated surface by dehydration or dehydrogenation.
In the present invention, the stain resistant agent contains the silicon-containing functional group (Xxe2x80x94Sixe2x80x94Oxe2x80x94) which combines by the dehydration or dehydrogenation with the hydroxyl group (xe2x80x94OH) present on the treated surface such as a glazed surface, thereby shielding the hydroxyl group. Accordingly, even when used water contains a large quantity of metal ion such as soluble silica, the hydroxyl group is already disabled or ineffective such that the hydroxyl group does not combine with any metal ion and accordingly with any component of human waste etc. Particularly even when used water contains soluble silica as the metal ion, the soluble silica is not deposited or is not apt to be deposited as silicic acid with network structure such that stain is not apt to be incorporated. Thus, if the stain resistant agent has the silicon-containing functional group, stain such as human waste is prevented from adhering to the ceramic product even when the ceramic product is used with water containing a large quantity of metal ion such as soluble silica, whereupon the ceramic product can easily be cleaned.
The silicon-containing functional group does not preferably combine with another silicon-containing functional group. According to the results of experiments conducted by the inventors, high scale, hairdye, wear and alkali resistances can be achieved. If the silicon-containing functional groups of the stain resistant agent combine with each other, silica is increased such that silicic acid with the network structure is deposited on the layer. Stain can be considered to be incorporated with the silicic acid.
Additionally, the silicon-containing functional group of the stain resistant agent has a durability as high as silica in the glazed surface of the ceramic product.
The stain resistant agent preferably contains a terminal carbon fluoride group combining with the silicon-containing functional group. Results of experiments conducted by the inventors show that the stain resistance also appears as water repellency by a small critical surface tension of the carbon fluoride group. Consequently, high scale, hairdye, wear and alkali resistances can be achieved.
The carbon fluoride group is preferably xe2x80x94CnF2n+1 where n is a natural number in a range of 1xe2x89xa6nxe2x89xa612. Results of experiments conducted by the inventors show that this increases fluoride and accordingly fluorosilane. Consequently, high scale, hairdye, wear and alkali resistances can be achieved.
The stain resistant agent preferably contains a terminal alkyl group combining with the silicon-containing functional group. Results of experiments conducted by the inventors show that the stain resistance also appears as lipstick stain and alkali resistances by a small critical surface tension of the alkyl group.
The stain resistant agent does not preferably contain any terminal alkali group combining with the silicon-containing functional group. Results of experiments conducted by the inventors show that this can achieve large scale, hairdye, wear and alkali resistances.
From the viewpoint of the wear resistance, a methyl group may be employed as the alkyl group. On the other hand, a propyl or hexyl group may be employed as the alkyl group from the viewpoint of alkali. Results of experiments conducted by the inventors show that when the alkyl group is a propyl or hexyl group, the alkyl group is increased. The stain resistant agent is advantageous in the alkali resistance but disadvantageous in the wear resistance. On the other hand, when the alkyl group is a methyl group, the stain resistant agent is advantageous in the wear resistance but disadvantageous in the alkali resistance.
The number of alkyl groups is perferably larger than the number of carbon fluoride groups when the stain resistant agent contains a terminal carbon fluoride group combining with the silicon-containing functional group and a terminal alkyl group combining with said silicon-containing functional group. Results of experiments conducted by the inventors show that the stain resistant agent does not contain only perfluoloalkylsilane. Consequently, the stain resistant agent has high lipstick stain wear resistances.
On the other hand, the number of carbon fluoride groups is preferably larger than the number of alkyl groups when the stain resistant agent contains a terminal carbon fluoride group combining with the silicon-containing functional group and a terminal alkyl group combining with said silicon-containing functional group. Results of experiments conducted by the inventors show that this increases perfluoloalkylsilane, resulting in high scale, hairdye, wear and alkali resistances.
The silicon-containing functional group and the alkyl group are preferably combined with each other by dimethyl siloxane (Oxe2x80x94Si(CH3)2). Results of experiments conducted by the inventors show that this results in high scale, hairdye, wear and alkali resistances.
The dimethyl siloxane preferably contains a straight chain combination of a silicon-containing functional group and an alkyl group or an annular combination of the silicon-containing functional group and the alkyl group. Results of experiments conducted by the inventors show that this results in stably high scale, hairdye, wear and alkali resistances.
As one example of the straight chain combination of the silicon-containing functional group and the alkyl group, an stain resistant agent containing a mixture of a first agent and a second agent described in Japanese Patent Application Publication No. 8-209118 (1996) may be employed. The first agent is a co-hydrolysate of an organic silicon compound containing a perphloroalkyl group and a methylpolysiloxane compound containing a hydrolytic group in a hydrophilic solvent, whereas the second agent is a mixture of organopolysiloxane and a strong acid. More specifically, the first agent is a co-hydrolysate of C8F17CH2CH2Si(OCH3)3 and Si(CH3O)3CH2CH2xe2x80x94(Si(CH3)2O)10xe2x80x94Si(CH3)2CH2CH2Si(OCH3)3 in a hydrophilic solvent containing a solution of 0.1 N-hydrochloric acid, t-butanol and hexane. The second agent is a mixture of HOxe2x80x94(Si(CH3)2O)30xe2x80x94Si(CH3)2OH and methanesulfonic acid.
A large effect can be achieved in a case where the treated surface is repeatedly wetted and dried. In a portion repeatedly wetted and dried, a metal ion in the water easily combines with a hydroxyl group, whereupon stain tends to be produced. In this meaning, the ceramic product of the present invention is effective when it is a Western style flush toilet, a Japanese style flush toilet, a flush toilet for men or a basin.
An antibacterial treatment may be applied to portions other than the treated surface.
When the stain resistant treatment of the present invention is applied to a treated surface which has already been stained, a ceramic product to which no stain resistant treatment has been applied can be changed to a treated ceramic product, or the reduced stain resistant effect of the ceramic product can be improved.
The method preferably comprises a pretreatment step of reproducing a hydroxyl group on the treated surface. Consequently, the layer can exhibit high durability. As the pretreatment step, the treated surface may be rubbed using an abrasive or acid ammonium fluoride or hydrofluoric acid may be applied to the treated surface and thereafter, the treated surface may be washed in order that stain due to silicic acid (stain due to scale) may be eliminated. Furthermore, the pretreatment step may include a first step where the treated surface is washed with an acid liquid so that stain due to urine is eliminated and a second step where the treated surface is rubbed using an abrasive subsequent to the first step, or acid ammonium fluoride or hydrofluoric acid is applied to the treated surface and thereafter, the treated surface is washed so that stain due to silicic acid (stain due to scale) is eliminated.